How to Grow New Zealand Flax  – Phormium 

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Phormium – commonly called New Zealand flax –is a dramatic plant composed of sword-like, stiffly vertical leaves in a fan pattern. Cultivars often range in colors from yellow-green to dark green with white or yellow stripes.

Phormium bears tall erect panicles of 1 to 2-inch (5cm) tubular blossoms in dull red or yellow. Flowers appear in late summer and autumn.

Use Phormium as an accent plant in a border, lawn, or near a building. Phormium is sturdy and fast-growing. Phormium can tolerate salt air and ocean spray. It can be easily grown as a container plant.

Phormium is a genus of two species of evergreen perennials native to scrub and swamps and hillsides near riverbanks in New Zealand.

Variegated Phormium
Variegated Phormium

Get to know Phormium 

  • Plant type: Evergreen perennial 
  • Growing zones and range: Zones 9 and 10 
  • Hardiness: Generally Zone 9 south 
  • Height and width: 5 to 7 feet (1.5-2m) tall and 4 feet wide (1.2m) 
  • Growth rate: Fast 
  • Form and habit: Clump-forming 
  • Foliage: Large, linear, keeled leaves, each folded into a V-shape at the base, and ranging in color from yellow-green to dark green, with many fine stripes 
  • Flowers: Abundant small, 1-2 inch (2.5-5cm), tubular 6-petaled, dull red or yellow flowers are produced in erect panicles on leafless stems 
  • Bloom time: Summer 
  • Uses: Border, by a building, at the edge of a lawn, coastal garden, accent plants, near swimming pools, specimen 
  • Common name: New Zealand flax 
  • Botanical name: Phormium 
  • Family name: Agavaceae 
  • Origin: New Zealand 

Where to plant Phormium 

  • Plant Phormium in full sun. 
  • Plant Phormium in fertile, moist but well-drained soil. 
  • Where marginally hardy, provide a deep, dry mulch in winter. 
  • Phormium tolerate salt air and ocean spray, but not dune conditions. 
  • In areas where they are marginally hardy, select a sheltered, south-facing site and protect plants with a thick layer of dry mulch such as salt hay or weed-free straw over winter.  

When to plant Phormium 

  • Sow Phormium seed at 55-64°F (13-18°C) in spring. 
  • Set container-grown Phormium in the garden in spring or autumn.
New Zealand Flax, red striped Sundowner variety
New Zealand Flax, red striped Sundowner variety

Planting and spacing Phormium 

  • Space Phormium 6 to 10 feet (2-3m) apart.

How to water and feed Phormium 

  • Give Phormium much or little water. 
  • Feed Phormium with an all-purpose organic fertilizer in spring. 

How to care for Phormium 

  • Where Phormium is marginally hardy, place a deep, dry mulch over the crown in winter or overwinter the plant indoors.

Phormium pests and diseases 

  • Phormium can sometimes develop leaf spots or crown rot. 
Flowering New Zealand Flax, Phormium tenax
Flowering New Zealand Flax, Phormium tenax

Phormium propagation 

  • Divide Phormium clumps in spring. 
  • Sow seed in warming soil or in a warming cold frame in spring.

Phormium varieties to grow 

  • Phormium cookianum, Mountain flax, clump-forming perennial ith broad, arching, linear, light to yellowish green leaves, to 5 feet (1.5m) long. Tubular, yellow-green flowers, to 1.5 feet (4cm) long, are produced in upright panicles, 6 feet (2m) long, in summer. To 6 feet (2m) tall and 10 feet (3m) wide. New Zealand. 
  • P. tenax, New Zealand flax, clump-forming perennial with rigid, upright, linear leaves, to 10 feet (3m) long, dark green above, blue-green beneath. Thick, red-purple panicles, to 12 feet (4m) long, of tubular, dull red flowers, 2 inches (5cm) long, are borne in summer. To 12 feet (4m) tall and 6 feet (2m) wide. New Zealand.    

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

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